My great grandmother passed away earlier this year and I have been thinking about building a drinking well in her name. If the well is built in her name even though she is not the one assisting to have it built would she receive the blessings from this well?

Yes you can do that as good virtue for your grandmother.

It was narrated from Sa’d bin ‘Ubadah that his mother died. He said:
“O Messenger of Allah, my mother has died; can I give charity on her behalf?” He said: “Yes.” He said: “What kind of charity is best?” He said: “Providing drinking water.” And that is the drinking-fountain of Sa’d in Al-Madinah.
Reference : Sunan an-Nasa’i 3666
In-book reference : Book 30, Hadith 56
English translation : Vol. 4, Book 30, Hadith 3696